| 摘要 |
Provided is a steel sheet for giving members by hot stamping, the members having excellent fatigue properties equal to those of ordinary high-strength steel sheets that have the same strength as the steel sheet. Also provided is a process for producing the steel sheet. The steel sheet for hot-stamped members contains, in terms of mass%, 0.15-0.35% C, 0.01-1.0% Si, 0.3-2.3% Mn, and 0.01-0.5% Al, with the remainder comprising Fe and incidental impurities, wherein the impurities comprise up to 0.03% P, up to 0.02% S, and up to 0.1% N as chemical components. The steel sheet is characterized in that the Vickers hardnesses of the steel sheet measured at sites located at a distance of 20 µm from a surface of the steel sheet toward the sheet thickness direction have a standard deviation of 20 or less. This steel sheet is produced through a recrystallization annealing step comprising: a first stage in which a cold-rolled steel sheet obtained by hot-rolling and then cold-rolling a steel that contains the chemical components is heated from room temperature to 600-700ºC at an average heating rate of 8-25 ºC/sec; and a second stage in which the steel sheet is successively heated to 720-820ºC at an average heating rate of 1-7 ºC/sec. |
